An optical fiber is a transparent thin fiber, usually made of glass or plastic, for transmitting light. The optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. In addition to transferring data, fibers can also be used as light guides or fiber optic illuminators.
The light transmitted through the fiber is confined due to total internal reflection within the material. This is an important property that eliminates signal crosstalk between fibers within the cable and allows the routing of the cable with twists and turns. Because of the remarkably low loss and excellent linearity and dispersion behavior of single-mode optical fiber, data rates of up to 40 gigabits per second are available in real-world use on a single wavelength. Wavelength division multiplexing can then be used to allow many wavelengths to be used at once on a single fiber, allowing a single fiber to bear an aggregate bandwidth measured in terabits per second.
Optical fiber is used in vehicles such as airplanes and automobiles. Optical fiber is used in automobiles that have a Media Oriented Systems Transport (MOST) bus. The MOST bus is a multimedia fiber-optic point-to-point network implemented in a ring, star or daisy-chain topology over plastic optical fibers. The MOST bus specifications define a Physical (Electrical and Optical parameters) Layer as well as an Application Layer, a Network Layer, and Medium Access Control. The MOST bus provides an optical solution for automotive media networks such as video and audio.
Fiber optic light guides are used in applications where bright light needs to be brought to bear on a target without a clear line-of-sight path. Fiber optic illuminators can create a uniform visual effect over lengths of up to 130 feet/40 meters, depending on the illuminator and desired level of brightness.
Light emitters are a key element in any fiber optic system. Lasers or Light Emitting Diodes (LEDs) may be used as light emitters to illuminate light guides or fiber optic illuminators. An LED converts the electrical signal into a corresponding light signal that can be injected into the fiber. The light emitter is an important element because its characteristics often strongly influence the final performance limits of a given link. LEDs are complex semiconductors that convert an electrical current into light. The conversion process is fairly efficient in that it generates little heat compared to incandescent lights. LEDs are of interest for fiber optics because of five inherent characteristics: 1) They are small, 2) They possess high radiance (i.e., They emit lots of light in a small area), 3) The emitting area is small, comparable to the dimensions of optical fibers 4) They have a very long life, offering high reliability and 5) They can be modulated (turned off and on) at high speeds.